johnson



E. H. JOHNSON.

'11113111.1111 ELECTRIC GONDUIT.

Patented June 16,1891.

(No Model.)

me wams uns co., mow-uma, msnmumu, n. c.

UNITED STATES PATENT OEEIcE.

EDVARD H. JOHNSON, OF NEV YORK, N. Y.

TUBULAR ELECTRIC CONDUIT.

SPECIFICATION forming part of Letters Patent No. 454,275, dated J' une 16, 1891.

Application filed September l5, 1890. Serial No. 364,966. [No model.)

To @ZZ whom, it may concern:

Be it known that I, EDWARD H. JOHNSON, a citizen of the United States, residing at New York city, in the county and State-of New York, have invented a certain new and useful Improvement in Tubular Electric 'Conduits, of which the following is a specification.

The object of my invention is to provide a tube to serve as the wireway for electrical conductors, which shall be strong, durable, of high insulating properties, and water-proof.

In carrying out my invention I employ a number of tubes of different diameters adapted to slip one into another. These tubes preferably are made of paper or other fibrous porous material, combined with an insulating compound, such as black petroleum pitch, the insulating compound and the paper base being combined by immersing the latter in a bathof insulating` compound maintained in a liquid state by high heat a number of times with a period of rest between immersions. Tubes so prepared or otherwise suitably prepared to form an insulating-body are cut, preferably, into equal lengths, say, of ten feet, and the tubes of smaller-diameter slipped half-way into the tubes of next larger diameter, a cementing substance, preferably, also, an insulating substance, such as asphaltum, being applied to the outside of the smaller tubes before slipping them into the larger ones, so that the tubes will be cemented .together and form practically one tube, the joint between the inner tubes being covered by the outer tube. In this Way any desirable length of tube is prepared, and also any desirable thickness of tube, the joints of each line of tubing going to form the entire or compound tube being protected by the nextouter covering, the joints of the covering-tube coming about midway from the ends of the inner tube and the joints of the last covering-tube being provided with, a covering-collar- In other words, the compound tube is made up of any number of thicknesses of individual tubes slipped one over the other and cemented together, all the tubes breaking joints.

In the accompanying drawings, forming a part of this speciiication, Figure l is a plan 5o view of a compound tubeof two thicknesses embodying my invention, and'Fig. 2 is a longitudinal central section of the same.

A are the several lengths of inner tube.

B are the lengths of the outer tube.

C are the joints between the lengths of inner tube, and D is the joint bet-Ween the outer tubes, coming about midway between the joints C C. E is the cemeutiug substance used to secure the tubes of one diameter to those of the next larger diameter. This cementing substance is applied on the outside of the inner tube before the insertion of the same into the next larger tube, with which it forms a comparatively tight fit, so that the ce inenting substance will be spread uniformly between the two tubes.

F is the collar closing the joints of the last outer covering.

My improved compound tube not only possesses advantages of durability, insulating and waterproofing qualities, but also possesses advantages for the factory, for transportation, and for application.

In the factory, instead of making up tubes for use of varying thicknesses, all the tubes are made of the same thickness, but of increasing diameters, so that one may be fitted within the other.

For transportation, the tubes may be nested and a large quantity shipped, occupying but a small space.

The user may build up his tube to any desired thickness when applying the same, as the necessity for using different thicknesses arises in the course of application. Vhen completed, he will have a tube superior to tubes madeup of concentric thicknesses of material formed on the same mandrel.

That I claim is- 1. The combination, in a compound tube for electrical purposes, of two or more series of lengths of tubing of insulating material of different diameters and of continuous crosssection, one series of tubing being slipped within the series next larger in diameter and breaking joints therewith, and a cemeutiug substance between each series of tubmg, also of insulating material, substantially as set forth..

2. The combination, in a compound tube IOO for electrical purposes, of two or more series break joint therewith, a oeinenting material of lengths of tubing of diiterent diameters binding the two series of tubing together, and formed of paper impregnated with an iusuu collar for the joints of the outer series ot lztting compound, one series of tubing being tubing, substantially as set `forth.

5 slipped within the series of nextlarger diume- This specification signed and witnessed 15 ter und cemented thereto undbreaking joints this 10th day ot' September, 1890. therewith, substantially as set forth. EDWD. H. JOHNSON.

A compound tube comprising a series ot "Witnesses: lengths of tubing slipped in another series of \V. PELZER,

1o lengths 0f tubing larger in diameter, so :is to .E CONRAU. 

